I had an idea to make 5 or 7 small TDM maps which "join" by either winning or loosing the round, so:

Teams start on map 3 (of 5) and if red win, a server bot changes the map to map 2 (of 5), if the blue win the map advances to map 4 (of 5). All maps would use the same textures / shaders but be packed individually.